get input Text from JTextField (string to char) to show up in JButton

Question

(new rewritten code).. I just know that "b" will always the last box that i created.So i can't use b as the equals in actionPerformed. How to include all the buttons? Anyone can help me with this? import java.awt.; import javax.swing.; import java.awt.event.*;

public class Lat1 extends JFrame implements ActionListener
{
    final int ROWS = 12;

    final int COLS = 12;

    final static int topLeftNum[][]= {
     {-1, 1, 0, 2, 0, 0, 3, -1, 4, 0, 5, 0},
        {6, 0, 0, 0, -1, -1, 0, -1, -1, -1, 0, -1},
        {-1, 0, -1, 0, -1, 7, 0, 0, 8, -1, 0, -1},
        {9, 0, 0, 0, 10, -1, -1, -1, 11, 0, 0, -1},
        {0, -1, -1, 12, 0, 0, 13, -1, 0, -1, -1, -1},
        {0, -1, 14, -1, 0, -1, 0, -1, 15, 0, 0, 16},
        {17, 0, 0, 18, 0, -1, 19, 20, 0, -1, -1, 0},
        {0, -1, 0, 0, -1, 21, 0, 0, 0, -1, -1, 0},
        {22, 23, 0, 0, -1, 0, -1, 0, -1,24, 0, 0},
        {-1, 0, -1, 25, 0, 0, -1, 0, -1, 0, -1, -1},
        {26, 0, 0, -1, -1, 0, -1, 27, 0, 0, 0, -1},
        {-1, -1, -1, -1, -1, 0, -1, 0, -1, 0, -1, -1}
        };

     Box b;

     JTextField t;

     char answer;

     public static void main(String[] args)
    {

     SwingUtilities.invokeLater(new Runnable() 
     {

      public void run(){ new Lat1(); }
     });
    }

    /*--------------------------------------------------------*/
    public Lat1() 
    { 

    this.setSize(1000,1000);
    this.setVisible(true);
     JPanel p1 = new JPanel(); 
     p1.setLayout(new GridLayout(ROWS,COLS));
     for (int j=0; j<ROWS; j++) {
      for (int i=0; i<COLS; i++) {
       b = new Box(i, //the boxes index
       (topLeftNum[j][i] < 0) ? Color.BLACK : Color.WHITE, //pick the color
       topLeftNum[j][i], //the topleft number
       answer, //the char inside
       this); //the action listener for the button
       p1.add(b);
      }
     }
     p1.setVisible(true);
     this.getContentPane().add(p1,BorderLayout.CENTER);
     this.pack();

     JPanel p2 = new JPanel();
     t = new JTextField(10);
     p2.add(t);
     p2.setVisible(true);
     this.getContentPane().add(p2,BorderLayout.SOUTH);

    }
/*-----------------------------------------------------------*/
public void actionPerformed(ActionEvent e) 
{
    for (int j=0; j<ROWS; j++) {
     for (int i=0; i<COLS; i++) {
    String numstr = String.valueOf(topLeftNum[j][i]);  
    if(e.getSource() == numstr && (t.getText()).length() == 1)
    answer = t.getText().charAt(0);
    b.setText(""+ answer);

    //b.setText(String.valueOf(t.getText().charAt(0));
     }
    }
}   
}

/*------------------------------------------------------------*/

class Box extends JButton

{

    public int index;

    private String topLeftNum;

    public Box(int index, Color color, int topLeftNum, char c, ActionListener al) 

    {


    this.setBackground(color);

     if (color != Color.BLACK) {

      this.setFont(new Font("SansSerif", Font.ITALIC, 20));

      this.setText(""+ c);

      this.addActionListener(al);

      this.index = index;

      if (topLeftNum != 0)

      this.topLeftNum = topLeftNum+""; }

     else {

      this.setText("");

      this.setEnabled(false);

      return; }

    }

    public void paintComponent(Graphics g) 

    {

    super.paintComponent(g); // paints background

    g.setFont(new Font("SansSerif", Font.PLAIN, 8));

     if (topLeftNum != null) g.drawString(topLeftNum, 5, 10);

    }

}
/*----------------------------------------------------------*/

Answer 1

First of all, You have NullPointerException thrown at line 59 from constructor of main class. You attempt to getText from field which is not initialized.

Secondly You can call repaint method, so label changing code might look as follows:

public void keyReleased(KeyEvent e) {
  if(e.getKeyCode() == KeyEvent.VK_ENTER) {
    Field f = (Field)e.getSource();
    Box b = f.box;
    b.setText(f.getText());
    b.repaint();
    this.remove(f);
    this.add(f.box, b.index);
  }
}

This should probably force JButton to change its look.

(Advice for Your next posts: add indentation to Your code, please)

Answer 2

repainting will work, but i recommend calling

SwingUtilities.updateComponentTreeUI(b);

that will refresh the entire component plus any children.

N

Answer 3

You should be using an ActionListener and not a KeyListener. Although it is not the cuase of your problem it is the better design when using a JTextField.

Answer 4

You don't actually add the TextField to anything as far as I can tell either - and your processing inside actionPerformed fails to compile due to a mismatch between Object (the class returned by "e.getSource()" and int (your "b.index" value).

Also, "b" is always the last "box" you create. You're a long way from a solution here.